V

ECOSYSTEM ( EVS )

Aquatic and Terrestrial Ecosystem

  • Aquatic Ecosystem: Water-based environments (e.g., oceans, rivers, lakes, ponds).

  • Terrestrial Ecosystem: Land-based environments (e.g., forests, deserts, grasslands).

1.2.1 Natural Ecosystem

  • Ecosystems that exist naturally without significant human intervention.

  • Characterized by their self-regulating mechanisms and complex interdependencies.

  • Examples: Forests, oceans, deserts, grasslands.

1.2.2 Artificial Ecosystems

  • Ecosystems created and maintained by humans.

  • Often require human intervention for their sustenance and management.

  • Characterized by reduced biodiversity and simpler food webs.

  • Examples: Agricultural fields, aquariums, gardens, urban parks.

1.3 Structure of Ecosystem
1.3.1 Biotic (living) components

  • Producers: Organisms that synthesize their own food, primarily through photosynthesis (e.g., plants, algae).

  • Consumers: Organisms that obtain energy by feeding on other organisms. Divided into primary (herbivores), secondary (carnivores eating herbivores), and tertiary (carnivores eating other carnivores) consumers.

  • Decomposers: Organisms (e.g., bacteria, fungi) that break down dead organic matter, recycling nutrients back into the ecosystem.

1.3.2 Abiotic (non-living) components

  • Non-living chemical and physical parts of the environment that affect living organisms.

  • Examples: Sunlight, water, soil, minerals, temperature, pH, atmospheric gases.

1.4 Food chain and food web
1.4.1 Food Chain

  • A linear sequence showing how energy and nutrients are transferred from one organism to another through feeding.

  • It illustrates who eats whom in an ecosystem.

1.4.2 Food Web

  • A complex network of interconnected food chains in an ecosystem.

  • Shows multiple feeding relationships and pathways for energy flow, reflecting the reality of natural ecosystems more accurately.

1.5 Carbon, Nitrogen, Sulphur, Phosphorus cycle
1.5.1 Carbon Cycle

  • The biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

  • Key processes include photosynthesis, respiration, decomposition, and combustion.

1.5.2 Nitrogen Cycle

  • The process by which nitrogen is converted into various chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystems.

  • Essential for life, involving processes like nitrogen fixation, nitrification, assimilation, ammonification, and denitrification.

1.5.3 Sulphur Cycle

  • The collection of processes by which sulfur moves between rocks, waterways, and living systems.

  • Sulfur is released into the atmosphere through volcanic eruptions and decomposition, then deposited back to Earth via precipitation.

1.5.4 Phosphorus Cycle

  • The biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.

  • Distinct from other cycles as it does not involve a significant atmospheric gaseous phase; it's primarily sedimentary.

1.6 Global Warming

  • The long-term heating of Earth's climate system observed since the pre-industrial period (between 1850 and 1900) due to human activities.

  • Primarily driven by fossil fuel burning, which increases heat-trapping greenhouse gas levels in Earth's atmosphere.

1.6.1 Ozone Depletion

  • The thinning of the ozone layer in the Earth's upper atmosphere (stratosphere).

  • Primarily caused by the release of human-made chemicals containing chlorine or bromine (e.g., chlorofluorocarbons - CFCs), which break down ozone molecules.

  • Leads to increased ultraviolet (UV) radiation reaching the Earth's surface.